Monthly Archives: November, 2013

A strange maze in Cambridge

Photography by Carlos Dorce

Photography by Carlos Dorce

Next to the chapel of St. John Fisher in Cambridge there is this stone with a very big maze engraved on the surface. I didn’t play to find the correct way because it was full of children playing around it. Maybe next time!

Location: map

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The Sundial in Senate House Passage

Photography by Carlos Dorce

Photography by Carlos Dorce

You must walk through the Senate House Passage if you want to visit the King’s College. If you look at the building at your right (which is not the Senate House) you will see this wonderful sundial. I think that the building is part of the Gonville and Caius College but I am not sure about it.

Location: Senate House Passage (map)

Turing in Cambridge

Photography by Carlos Dorce

Photography by Carlos Dorce

Cambridge is full of this plaques with the names of the great scientists and humanists who studied and worked here. So you must look at these blue circles if you want to find the names of the great minds like Alan Turing (1912-1954), “mathematician, computer pioneer and code breaker”.

The plaque is in King’s Parade near the intersection with Bene’t St.

The sundial of St. Botolph’s Parish Church

Photography by Carlos Dorce

Photography by Carlos Dorce

There is a sundial on the tower of St. Botolph’s Parish Church in Cambridge. The dial has two faces oriented with the walls of the tower and this is its only peculiarity:

Photography by Carlos Dorce

Photography by Carlos Dorce

Location: St. Botolph’s Parish Church (map)

Hay’s Galleria in London

Photography by Carlos Dorce

Photography by Carlos Dorce

There is this strange metallic sculpture inside the Hay’s galleria in London. It represents a ship and it has something similar to an armilar sphere in the bow:

Photography by Carlos Dorce

Photography by Carlos Dorce

Location: Hay’s Galleria (map)

The National Maritime Museum

The National Maritime Museum is another of the touristic attractions which can be visited in Greenwich. Of course, you can see boats, ships, maps,… and all the things related to the sea and the English glorious past. Therefore… what can the mathematical tourist visit here? Navigators used charts, maps, astrolabes, globes,… in their adventures so we can start our mathematical visit with all these mathematical objects!

Photography by Carlos Dorce

Photography by Carlos Dorce

Brass celestial globe. German, about 1725

This is one of a pair with a terrestial globe. It shows constellations, the Milky Way and the Magellanic Clouds. It contains some mistakes, indicating that it was a luxury item that could adorna wealthy home rather than an up-to-date scientific instrument. Nevertheless, with its calendar ring, it could be used to identify what was seen in the night sky.

There also are terrestial globes which were used by navigators to measure distances on the terrestial surfaces:

Photography by Carlos Dorce

Photography by Carlos Dorce

The first golden globe is from 1600 and the globe at its right is a French globe from 1625. Behind it there is a German terrestial globe by Johann Reinhold (1588). Of course, sundials also are shown in the exhibition! The first one (left) is an inclining dial for use in Japan before 1872 and the second is an equinoctial dial fou use in Huangzou, China, in the 19th century:

Photography by Carlos Dorce

Photography by Carlos Dorce

We can also find astrolabes, compasses, quadrants, telescopes, rulers,…

Photography by Carlos Dorce

Photography by Carlos Dorce

Look at this astrolabe from Islamic Spain (c.1230) by an unknown maker! It’s a jewel!

Photography by Carlos Dorce

Photography by Carlos Dorce

I am sure that you can find out more mathematical objects if you have enough time to enjoy all the exhibition!

Location: National Maritime Museum in Greenwich (map)

The Royal Observatory in Greenwich (and III)

Source: Wikimedia Commons

The third step in the visit to the Royal Observatory of Greenwich is Flamsteed House.

The Royal Observatory of Greenwich was founded in 1675 when Charles II ordered that a small observatory be built in Greenwich Park and appointed John Flamsteed as his ‘astronomical observator’. Flamsteed’s task was to make observations that would improve astronomical navigation, in particular providing a means of finding longitude at sea.

Photography by Carlos Dorce

Photography by Carlos Dorce

The ceiling of the first room is painted with a map of the night sky and there are portraits of the ten Astronomers Royal who lived here between 1676 and 1948:

Photography by Carlos Dorce

Photography by Carlos Dorce

Christopher Wren was responsible for building the Observatory. He later said that it was designed ‘for the Observator’s habitation & a little for Pompe’. The following four rooms were Flamsteed’s living quarters. They were incorporated into the enlarged home of the Astronomer’s Royal over the next two and a half centuries. Beyond these, upstairs, is the magnificient Great Star Room, or Octagon Room.

ROG14

The Octagon Room by Francis Place (c. 1760)

The Octagon Room is one of the few surviving interiors designed by Wren and it was used mainly for observing eclipses, comets and other unusual celestial events.

The 32-inch Astronomical Quadrant is located in this room. It is signed by John Bird but the telescope which was once attached is missing.

Photography by Carlos Dorce

Photography by Carlos Dorce

The engraving of the Octagon Room by Francis Place shows a similar, earlier quadrant standing on a wheel-tripod platform, which allowed the astronomer to roll it from window to window.

On the wall behind the quadrant we can see three replicas of the clocks which were made in 1676 by Thomas Tompion and sold by Flamsteed’s widow some years later. There is also a replica telescope tube of the kind used here until 1765. Will my daughter be able to discover a new planet?

Photography by Carlos Dorce

Photography by Carlos Dorce

If we go downstairs now we’ll discover an exhibition about the determination of the longitude at sea:

Where am I?

At sea, navigation is a matter of life and death. Out of sight of land, how can you tell where you are?

By 1700, skilled seamen could find their position north or south (their latitude), but still lacked accurated instruments or methods to calculate their east-west position, known as longitude.

With growing international trade, the lives and valuable cargoes lost in shipwrecks made solving this ‘Longitude Problem’ urgent for all sea-going nations.

Photography by Carlos Dorce

Photography by Carlos Dorce

The exhibition starts with these two 17th-century globes from North Africa (left) and Persia (right) and then you meet the star of the ‘Longitude Problem’:

John Harrison Photography by Carlos Dorce

John Harrison (1693-1776) by Thomas King (c. 1766)
Photography by Carlos Dorce

Finding longitude – the timekeeper method

One solution to the Longitude Problem was an accurate and portable sea-going clock. By 1726, news of the Longitude Prize had reached John Harrison, a carpenter and self-taught clockmaker from Lincolnshire. Harrison was already making highly accurate land-based clocks and had solved major problems to do with temperature change and friction.

Harrison spent the next 45 years of his life developing portable sea-going timekeepers that would accurately, in spite of a ship’s motion and temperature changes. Each timekeeper represented years of obsessive labour.

By 1760, Harrison had solved the Longitude Problem with his fourth marine timekeeper, now known as H4. It is one of the most important machines ever made.

Photography by Carlos Dorce

Photography by Carlos Dorce

Harrison’s first timekeeper [H1]

This timekeeper took five years to build. In 1736, it was tested on a sea voyage to Lisbon and back. Harrison was very seasick, but the timekeeper worked. It was the most accurate sea-going clock then known, though not quite accurate enough to win the 20.000 pounds prize.

This prize was offered in 1734 by the British government for a ‘practical and useful’ method enabling ships to determine their longitude at sea.

In the exhibition there are also some timekeepers more and the portraits of some of the most important scientific men which lived in the same time as Harrison: Halley succeeded Flamsteed as Astronomer Royale and his major programme was to replace all the astronomical instruments which were sold by Flamsteed’s widow, and to chart the Moon’s 19-year cycle.

Edmund Halley Photography by Carlos Dorce

Edmund Halley by George White after G.Kneller (c.1721)
Photography by Carlos Dorce

Newton advised the Parliamentary committee that established the Longitude Prize and became a member of the Board of Longitude:

Sir Isaac Newton Photography by Carlos Dorce

Sir Isaac Newton by Jacobus Houbraken after G.Kneller (18th century)
Photography by Carlos Dorce

Finally, apart of the camera obscura, we can find outside the Family Tombstone of Halley which was moved to the Observatory from the churchyard of St. Margaret’s in Lee when Halley’s tomb was restored in 1854. The tomb itself is still located at St. Margaret’s with a replica tombstone in place:

Photography by Carlos Dorce

Photography by Carlos Dorce

As you have seen, you must visit the Royal Observatory in Greenwich if you visit London: it’s only a few metro stops from the center of the city!

LocationGreenwich Observatory (map)

The Royal Observatory in Greenwich (II)

Photography by Carlos Dorce

Photography by Carlos Dorce

The Royal Observatory of Greenwich was commisioned in 1675 by Charles II and the building was completed in the summer of 1676. John Flamsteed (1646-1719) was the first Astronomer Royal so the building was often given the title “Flamsteed House” in reference to its first occupant.

In one of the walls, the observatory has the Sepherd 24-hour Gate Clock which is the earliest electrically driven public clocks. It was installed in 1852 ans the dial always shows Greenwich Mean Time (GMT):

Photography by Carlos Dorce

Photography by Carlos Dorce

In the small plate under the clock (G 1692) is an Ordnance Survey bench mark dating from the 1940s. The height above the sea level has been measured and recorded. There are also the British Imperial Standards of Length which were mounted here some time before 1866.

The observatory is also known as the location of the prime meridian of Greenwich meridian:

Photography by Carlos Dorce

Photography by Carlos Dorce

All the tourist want to have a picture with a foot in each side of the meridian:

Photography by Carlos Dorce

Photography by Carlos Dorce

and there is always a large queue to take a picture next to the meridian line which is graved ion the terrace:

Photography by Carlos Dorce

Photography by Carlos Dorce

Another characteristic thing of the obervatory is the Time Ball. The red time ball on top of Flamsteed House is one of the world’s first visual time signals. It was installed in 1833 to enable navigators on ships in the Thames to check their marine chronometers.

The Time Ball drops daily at 13:00hrs (GMT in winter […]). It is raised halfway up the mast at 12:55hrs as a preparatory signal and to the top 2 minutes before it drops.

Photography by Carlos Dorce

Photography by Carlos Dorce

 Let’s start our visit through the gardens of the observatory where we can imagine the great English astronomers looking at the night sky! Ofcourse we find a sundial: 

Photography by Carlos Dorce

Photography by Carlos Dorce

Sundials are the oldest known device for telling the time. As the Earth rotates and the Sun appears to move accross the sky, the shadow cast on the scale indicates the time of the day.

This dial constructed in 1968, represents a globe made from a series of rings. The rings are called ‘armillae’ in Latin, so it is called an armillary dial. The hour scale is on the northern half of the ring representing the equator.

There is also the well where Flamsteed 100-foot telescope was located:

Photography by Carlos Dorce

Photography by Carlos Dorce

Flamsteed used a 30,5 m. well on this site to accomodate a very long telescope:

ROG09

The astronomer sat at the bottom of the well and observed stars that passed directly overhead. It was hoped that placing the telescope in the well would make it possible to create a steady long-focus instrument for very fine measurements. Flamsteed made a few observations from here in 1679, but the damp underground conditions soon made the telescope impossible to use.

A remaining section of a 12 m. reflecting telescope built for the astronomer William Herschel is also in the gardens:

Photography by Carlos Dorce

Photography by Carlos Dorce

The telescope was the largest in the world and cost over 4.000 pounds, paid for by King George III. Completed in 1789 and erected at Herschel’s home near Slough, about 30 miles (48 km) west of Greenwich, it soon became a tourist attraction. Some people likened it to the Colossus of Rhodes, and it was even marked on the 1830 Ordnance Survey map of the area.

Sadly, the Herschels did not use the great telescope for much serious astronomy since it was difficult to set up and mantain. William’s son had it dismantled in 1840. Most of the tube was destroyed when a tree fell on it 30 years later.

On the walls of Flamsteed House is marked  the Bradley Merdian which was the first British National Meridian. The Greenwich meridian was set according to the location of the telescope used by the Astronomer Royal to establish the time. So the Greenwich meridian was in the graved line when James Bradley, the 3rd Astronomer Royal between 1742 and 1762 was in the observatory. When the Airy Transit Circle Telescope was erected in 1850, the Greenwich Meridian was moved approximately 19 feet east to its present location.

Before visiting Flamsteed House there is still time for look at the Dolphin Sundial designed by Christopher St. J. H. Daniel and commisioned by the National Maritime Museum in 1977:

Photography by Carlos Dorce

Photography by Carlos Dorce

So let’s go now to Flamsteed House!

LocationGreenwich Observatory (map)

A chess in Warwick Lane

Photography by Carlos Dorce

Photography by Carlos Dorce

Go to Warwick Lane and you will see a frieze representing a chess! It’s just a curiosity but… enjoy it!

Photography by Carlos Dorce

Photography by Carlos Dorce

Location: 8 Warwick Lane in London (map)

Temple Bar in London

Photography by Carlos Dorce

Photography by Carlos Dorce

Temple Bar is the only surviving gateway into the City of London erected in 1672 at the behest of Charles II to replace a previous timber structure which had survived the Great Fire but was falling into disrepair. The new gateway was designed by Christopher Wren.

Nowadays, you can cross the gateway from St. Paul’s cathedral to a very cool new square…

Photography by Carlos Dorce

Photography by Carlos Dorce

…where you can find an analematic sundial in one of the facades:

Photography by Carlos Dorce

Photography by Carlos Dorce

Location: Temple Bar (map)